Recently, there have been known vehicles that are each capable of using electric power fed from a power supply which is external to the vehicle (hereinafter also referred to as “external power”) to charge a power storage device mounted on the vehicle (hereinafter also referred to as “external charging”). Such vehicles are also called plug-in vehicles and usually equipped with a charger for converting an externally fed AC (alternating current) into a DC (direct current) to output the DC to the power storage device. A circuit configuration of such a charger is disclosed for example in PTL 1 (Japanese Patent Laying-Open No. 8-107607).
The charger disclosed in PTL 1 is provided with a power converter including an inverter circuit, a switching bridge, and a diode bridge. The charger converts an AC that is input from the outside of the vehicle into a DC by means of a switching operation of the power converter while adjusting the power factor, and converts the DC which is input from the power converter into a high-frequency AC by means of a switching operation of the switching bridge and thereafter converts the AC back to a DC by means of the diode bridge to output the resultant DC to a battery. This charging mode is carried out in two steps (two stages), namely the power factor adjustment and the conversion to the high frequency AC, which involve the switching operations, and therefore also called dual-stage charging.